This year sees the maiden flight
of the thirteenth-generation Delta
launch vehicle, the Delta II, built
for the US Air Force but already
leading the US commercial
launcher market. Tim Furniss
describes the new vehicle, and
an uprated 14th version to be
introduced in 1990.
In May 13, 1960, Cape Canaveral was the scene of the maiden flight of the Thor Delta, a combination of the Thor
intermediate-range ballistic missile and an
Able upper stage from the Vanguard satellite
launcher. The vehicle, carrying the Echo
A-10 reflective balloon satellite, failed due to
a second-stage malfunction. It was the 25th
US launcher failure in 47 launch attempts.
Since then, the Thor Delta has become
known simply as the Delta. It has been
uprated 11 times, and has .maintained a 94
per cent success rate—176 successes out of
182 launches—or 98 per cent over the last
ten years, with 47 successes in 48 launches.
Now Delta II, the 13th version of the
McDonnell Douglas vehicle, is set to fly 12
missions a year for military and commercial
clients. The Delta II was conceived mainly
as a result of the Challenger disaster, and the
apparent inability of the Space Shuttle to
launch enough US Air Force Navstar II
Block 1 and Block 2 global positioning
satellites into orbit to meet the schedule. An
uprated 14th version is to be introduced in
1990.
The USAF issued requests for proposals
for a new Medium Launch Vehicle (MLV),
and on January 21, 1987, McDonnell
Douglas, which was about to shut down its
Delta production line before the Challenger
tragedy, won the $316-5 million contract
to build and launch seven Delta II MLVs.
The contract included an option on 13
more MLVs at a total value of $669 million.
The order has since been increased to 20
vehicles. The award of the contract con
veniently coincided with the entry into the
commercial market of MDC's existing Delta
3920, which first flew in 1982. Delta II later
joined it.
There is a tail to the US Air Force
contract, in the form of an additional $65
million in incentive awards. These comprise
An artist's impression of a Delta II launched from
Vandenberg
FLIGHT INTERNATIONAL, 7 January 1989 35